Real Life Torpedo loading

[Blacklight]

I've often wondered this. When my friend was giving me the tour of the sub he worked on (the San Juan (688i class)). When we were in the torpedo room, it looked like the tubes could be loaded pretty quickly (to my civilian, completely non naval eyes). It looked like it was just a case of openening the hatch, having the boys just shove the torpedo in there, and closing up the hatch.
Why does loading a tube take so long ? What process do they have to go through ? :hmm:
Just curious.

[Bill Nichols]

Of course you have to hook up the cables for connecting the torpedo to the fire control system, and the wire for wire-guidance. After that you do checks to ensure everything is hooked-up correctly and the torpedo is healthy.

[Chock]

I presume there would have to be some coordination with the people controlling the boat's ballast too, since an ADCAP weighs around three and half thousand pounds, so I imagine it would affect the boat's trim when it was shifted into the tube, thus doing it slower would allow the compensation in trim to be more carefully controlled (this is just a guess by the way, but it seems logical).

Chock

[Sea Demon]

Originally Posted by Chock

I presume there would have to be some coordination with the people controlling the boat's ballast too, since an ADCAP weighs around three and half thousand pounds, so I imagine it would affect the boat's trim when it was shifted into the tube, thus doing it slower would allow the compensation in trim to be more carefully controlled (this is just a guess by the way, but it seems logical).

Chock

I hadn't thought of that. And it does bring up an interesting question. But if that is the case, then what happens to trim once the weapon is launched and you're suddenly lighter up front? :hmm:

[Sonoboy]

Originally Posted by Sea Demon

I hadn't thought of that. And it does bring up an interesting question. But if that is the case, then what happens to trim once the weapon is launched and you're suddenly lighter up front? :hmm:

Don't be near periscope depth?


Be careful with big weapons all
In this cramped torpedo room
Should one slip and fall "You killed us all!"
The torpedo says "KABOOM!"
:rotfl:

[Rip]

The weight of the fishmoving from in the rack to tube stowed isn't that big a deal as the distance moved forward isn't that far. Even 3ooo moved from bow to stern only effects trim under 5kts. It is accounted for and compensated by the COW. there is also the moving of water for flooding and draining the tubes. There are numerous weight effect evolutions every day. Each coordinated and compensated for. From pumping the **** tanks to making water.

The loading of weapoms into the tube also rquires hooking and unhooking starps and hydraulic rams the manipulate/secure the weapon not to mention needing to pivot the trays to allow for the slight outward angle of the tubes. A shapr weapons loading team can load one pretty fast though. But they always excersize a good dose of caution as is required by the procedures.

Definately a lot less back breaking than loading them without the hydraulic "rabbits" though.

[Chock]

I do know WW2 subs had torpedo compensation tanks which would flood when the torpedoes launched, in order to keep the weight the same so the boat wouldn't broach, dunno about modern boats though, as losing a torpedo's weight on a modern boat would be a very small percentage of the overall weight, so it could probably be sorted with the normal trim tanks I would guess.

Chock

[Bubblehead Nuke]

I may be a nuke, but being the busybody that I was, I have watched the evolution MANY times.

We are going to start with a simple scenario:

1)The torpedo needed to go in the tube is already stowed in front of the tube it needs to go in.

2)The Torpedo tube is already empty.

Now, then ordered to load the tube, they have to angle to torpedo to line up with the torpedo tube. The tubes are canted outwards, the torpedo's themselves are stowed in a direct fore to aft configuration.

One a 688 the two outward stowage trays (4 stows per tray) are designed to cant inward at the rear of the to line up the inboard stows of this tray with the tubes directly ahead of them.

The torpedo tube is verified dry and the outer door shut. The weapon is then unstrapped and lifted on a array of rollers that 'pop up' when the tie down straps are released. The nose cone cover is removed (easy and quick to do). The inner door is then opened and the torpedo is rammed home via a hydraulic shuttle. The speed of the weapon load is determined by the hand that controls the hydraulics. Yes, there are safety limts, but if your butt is on the line, you CAN load faster.

Now, the weapon is in the tube. They hook up the umbilical and the 'wire', and close the inner door. Folks, this is QUICK.

Once the weapon is in the tube they can power it up the same time they are flooding the tube. From there is is tell the weapon who to kill and launch the puppy.

Now, lets complicate it some. Lets put a weapon in the tube, and the weapon you WANT in the center rack on the bottom.

You first, have to index your weapons to get an EMPTY slot behind the tube. Normally, you have ONE empty lot on the room. You want to go out with as many weapons as you can. The whole tray can't move laterally to be next to the center tray. We have an 'bridge/elevator' that can move up and down between the outer trays and the center tray. Thus you have to start a puzzle type game where you are moving the weapon left or right while at the same time moving weapons up and/or down these elevators. After a little while you finially get an open slot behind the tube you want to unload. Now you have to open the inner door, hook up to the hydaulic shuttle and pull your umbilical before you can extract the weapon. If you mess up the connection you now have a DEAD weapon in your room, so you have to be careful. Once you have the weapon on the tray, you have to secure it, then you can move it around to get the weapon you WANT in the correct position. Each time you load or unload a weapon you have to pivot your outer tray which means you are done moving weapons till you can put the tray back in the original position.

As you can see, it can take a SIGNIFICANT amount of time to move that weapon to the outboard tray to be able to load it.

The question was asked about trim shift when you launch a weapon. From my understanding there is some, but not much as you are replacing the weight of the weapon with a large volumn of water in the now empty torpedo tube once the torpedo is fired. Once you close the outer door, the water is drained inboard into a trim tank inside the boat so again, you have not lost a large amount of weight from the front. The same thing happens when you launch a VLS weapon. The tube is filled with water so you stil have a significant amount of weight in the tube thus not effecting trim that much. How do you think a boomer would stay down if they had shot their load?

[TopTorp '92]

Originally Posted by Blacklight

Why does loading a tube take so long ? What process do they have to go through ? :hmm:
Just curious.

We did loads/reloads in 8 min or less. It takes long depending on the number of team members present. Experience plays the decisive role.

Ordinance Document (OD) 44979 spells out the procedure.

During the tube loading procedure the torpedoman must remove the exploder safety screw. That screw is what prevents the warhead from arming while the torpedo sits anywhere outside the tube (like on the rack or somewhere on the pier.) The idea was to prevent the torpedo from arming in a hot-run situation. It sticks out by about 1/2'' or so. Failure to remove the screw will result in a sheered screw virtually impossible to remove by any allowable means AND it turns a mult-million dollar weapon into a dud. I've read and heard stories about a torpedoman using an electric drill on the exploder to remove the carcas. Highly illegal according to the OD 44979 and potentially suicidal for the submarine to do so. Do you REALLY want to create excessive vibrations in the exploder of a warhead? Didn't think so.

Once the torpedo has been tube loaded, the arming rod is kept in check by the inner walls of the tube. So, here too it is impossible for the exploder to arm while inside the tube.

Then the fire control team will test the torpedo communication link by applying power and following an additional OD 44979 procedure. Analog MK-48 took longer while digital ADCAP was/is faster (fewer moving parts.)

Top Torp